<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="watch">
        <p>
            请问一个问题：
            <input  v-model="question">    
        </p>
        <p>{{answer}}</p>
    </div>
    <script src="js/vue.global.js"></script>
    <script>
        const watche = Vue.createApp({
            data() {
                return {
                    question: '',
                    answer: '好问题'
                }
            },
            watch: {
                questiond(newValue, oldValue) {
                    this.answer = newValue
                    console.log(oldValue)
                }
            }
        }).mount('#watch');
    </script>
    </div>
</body>
</html>